Rumi's "Table Talk"

The master said there is one thing in this world which must never be forgotten.  If you were to forget everything else, but were not to forget this, there would be no cause to worry, while if you remembered, performed and attended to everything else, but forgot that one thing, you would in fact have done nothing whatsoever.  It is as if a king had sent you to a country to carry out one special, specific task.  You go to the country and perform a hundred other tasks, but if you have not performed the task you were sent for, it is as if you have performed nothing at all.  So man has come into the world for a particular task, and that is his purpose.  If he doesn't perform it, he will have done nothing.